ORANGE FARM, South Africa -- For those who believe cheap drugs alone will beat back Africa's AIDS epidemic, consider the struggle of Patience Morare. Ms. Morare, a 51-year-old retired nurse, is on the front lines of the fight against a curable but no less deadly scourge: tuberculosis.

Seven days a week, she and 22 full-time volunteers pound the red dirt roads that crisscross this sprawling slum of more than 250,000 people outside of Johannesburg. They walk from shack to shack explaining the dangers of TB, supervising the...